On my Roadster the difference was more subtle, better but hard to pin down why.
What did stand out though was the Panhard rod eliminated rear wheel steer under hard acceleration. I didn't expect that.
Dave, I think the rear wheel steer und hard acceleration appeares because Series 1 has only one anti tramp bar. Then under acceleration one side of the axle is rigid under control and the other side is free floating to the front and the back which generates a steering effect. I am not really a fan of panhard rods with the Morgan for other reasons but a second anti tramp bar should solve this issue. So I did it with my series 3 Roadster Sport.